Add Payout Amount

**User Story:**
As a funder
I want to be able to add a payout amount for my bounty pegged to the selected token or USD
So that I can clearly articulate the payout amount of my bounty

**Acceptance Criteria**

**Form Initiation - Payout Amount Disabled**
GIVEN I am on the payout step of the bounty creation form
AND the form is clean - no changes has been made on the form
THEN the payout amount fields should be disabled
- Amount
- Amount (USD)
- Peg to USD

**Enable Payout Amount Fields**
GIVEN I am on the payout step of the bounty creation form
WHEN i select a chain
AND i select a token
THEN by default the payout amount should be defaulted Peg to USD = True
AND the amount field should:
-Show the selected token abbreviation
- be zeroed
- disabled
AND the amount (USD) field should be enabled

**Entering Amount (USD)**
GIVEN I am on the payout step of the bounty creation form
AND i have the payout amount pegged to USD
WHEN i enter a number value in the Amount (USD) field
THEN the system should take that value and convert it to the amount of the selected token
AND that converted value should display in the DISABLED Amount field

**Pegging to Native Token**
GIVEN I am on the payout step of the bounty creation form
AND i have the payout amount pegged to USD
WHEN i deslect the peg to USD checkbox
THEN the Amount field should be enabled
AND the amount (USD) field should be disabled

**Entering Native Amount**
GIVEN i am on the payout step of bounty creation
AND i have the payout amount pegged to my native token
WHEN i enter a number value in the Amount field
THEN the system should convert that value to USD at the time of entry
AND that converted value should show in in the DISABLED Amount (USD) field

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**Product & Design Links:**

**Tech Details:**

**Open Questions:**

**Notes/Assumptions:**

No files or tests are named. Start by locating the bounty creation form's payout step and trace how chain, token, and token/USD pricing are represented. Implement the stated disabled, default, conversion, and checkbox-toggle behavior, then verify each acceptance criterion through the form.

Written by the indexing model from the issue text.